Pump or fluid motor of the gear type



y 5, 1956 B. H. MOSBACHER PUMP 0R FLUID MOTOR OF THE GEAR TYPE 3 Sheets-Sheet 1 Filed June 1, 1953 177%?72/07 51M 34! WW flyW GNL W vZ/IIs'.

May 15, 1956 B. H. MOSBACHER PUMP OR FLUID MOTOR OF THE GEAR TYPE 3 Sheets-Sheet 2 Filed June 1, 1953 May 15, 1956 B. H. MOSBACHER M 7 ,7 z w t 4} X3 j United States Patent PUMP 0R FLUID MOTOR on THE GEAR TYPE Bruce H. Mosbacher, Rockford, 111., assignor to Geo. D. Roper Corporation, Rockford, 11]., a corporation of Illinois Application June 1, 1953', Serial No. 358,625

14 Claims. (Cl. 103-117) This invention relates to a novel pump or fluid motor of the type which employs a plurality of rotary gears for displacing the fluid.

It is an object of this invention to provide a novel and improved pump or fluid motor of the type having rotary gears in the fluid displacement mechanism.

It is also an object of this invention to provide a novel pump or fluid motor of this general type which is adapted for pumping water, abrasive liquids and other fluids which conventional gear pumps have been found to be impractical to handle.

Another object of this invention is to provide a novel pump or fluid motor of the gear type having reduced wear on the moving parts due to the absence or" metalto-metal contact thereat.

Another object of this invention is to provide a novel pump or fluid motor of the gear type which is quieter in operation than conventional devices of this. type.

An additional object of this invention is to provide a pump or fluid motor of the gear type of novel construction in which the drive load is distributed across the periphery of the gears and which avoids concentrating the drive load at line contact between the gears, as is the case in conventional gear pumps.

A further object of this invention. is to provide a.- pump or fluid motor of the gear type which is of novel construction enabling the use ofsoft plastic gears in thefluid displacement mechanism, thereby reducing the cost of the device as compared with devices of this type which require metal gears.

A still further object of this invention is to provide a novel pump or fluid motor of'the gear type having twice the fluid displacement for a given tooth depth of con.- ventional gear pumps of fluid motors.

Yet another object of this invention: is to provide a pump or fluid motor of the gear type which, is of novel construction in which the bearing loads are lessened because of the reduced projected areas of the gears exposed to the fluid under high pressure.

Also, it is an object of this invention to provide a novel pump or fluid motor of the gear type in which all of the gears turn in the same direction.

The foregoing objects and advantages of the present invention are preferably accomplished by mechanism which includes a plurality of spaced rotary gears, an end.- less flexible toothed belt extending around the gears in driving relation therewith, and spaced low pressure and high pressure passages communicating with the intertooth spaces on the gears and the belt for the displacement of fluid as the gears rotate and the belt turns therewith.

Other and further objects and advantages of the present 2,745,355 Patented May 15, 1956 'ice embodiment of the present invention, taken along the line 11 in Fig. 2;

Figure 2 is a longitudinal section through the Fig. 1 device, taken along the line 22 in Fig. 1-;

Figure 3 is a longitudinal sectional view of a second, four-gear embodiment of the present invention;

Figure 4 is alongitudinal'sectional view of a third, three-gear embodiment of the present invention; and 1 Figure :5 is a longitudinal sectional view of a fourth, multiple-gear embodiment of the present invention wherein the belt meshes with gears at both its inner and outer faces.

Referring to the first embodiment of the invention, shown in Figs. 1 and 2, the pump or motor includes a spaced pair of spur gears 10 and 11 which are of conventional design, having gear teethentirely around their respective peripheries. The gears are out of meshing re.- lationship with one another, beingseparated by a fixed spacer plate 12, which has arcuate end faces 13 and 14 providing close running fits for the mutually adjacent, inwardly facing peripheral portions of the gears. An endless flexible belt 15- extends around the gears and the spacer plate. This belt is formed at its inner face with teeth or lugs 16 which mesh closely with the teeth on the gears, as best seen in Fig 2, so that the beltis in driving relation with both gears; Between the gears the spacer plate 12 presents opposite flat end faces 17, 18 which provide close running clearances for the toothed inner face of the belt thereat.

The endless flexible belt 15 is preferably of the type known as the Gilmer timing belt, which has come into extensive use as a power transmission medium wherea non-slip power transmission or precise synchronization between two or more rotary shafts is required. This belt is preferably of cabled steel wire embedded in neoprene at the outer side of the belt, a plurality of spaced, relatively hard neoprene teeth at the inner side of the belt, and a neoprene-impregnated fabric layer serving as a facing for the inner face of the belt.

The entire assembly of the gears 10, 11, spacer plate 12, and belt 15 is enclosed within a housing (Fig. l) consisting'of the spaced end plates '19 and 20-, and the intermediate casing member 21 clamped between the end plates, with resilient gaskets: 22, 23 interposed therebetween. As shown, the gasket 23 provides a close running clearance for the gears at one end face thereof, while at. the opposite end faces of the gears the intermediate casing member 21 is formed with a transverse shoulder 24, which provides close running fits for the gears thereat. Between its shoulder 24 and the gasket 23 the intermediate casing member 21 defines an oblong chamber 25 of'the configuration indicated in Fig. 2. The smooth outer face of the timing belt 15 has a close running fit in this chamber substantially completely around the belt, as indicated in Fig. 2.

Referring to Fig. 1, the gear 10' carries an integral journal 10a which is rotatably received in a passage 26 formed in the intermediate casing member 21 extending from the internal shoulder 24 thereon to the gasket 22. At its opposite end the gear 10 carries an integral journal 10b rotatably supported by a cylindrical bearing bushing 27, which is snugly received within a cylindrical cavity 28 in the. end plate 20 extending outwardly from the gasket 23. The gear 11 carries integral journals 11a and 11b at its opposite ends which are supported for rotation by bearing sleeves 29 and 30 disposed respectively in cavities 31 and 32 in the intermediate end housing members 21 and 2.0, respectively.

For introducing fluid into the chamber 25, when the device is operated as a pump, the intermediate casing member 21 is formed with a threaded inlet passage 33 which leads to a low presspre passage 34 extending cornpletelyacross the housing chamber 25. As shown in Fig. 2, the passage 34 communicates with the space between the gearll, the toothed inner face of the belt 15 and the upper right corner of the spacer plate 12 in Fig. 2, immediately adjacent the location where the'belt engages the 'gear'll. The passage 34 also extends across the outer face of the belt here; otherwise, fluid pressure unbalance on theopposite faces of the belt might force the belt tootightly against the wall of chamber 25. Alternatively, for this purpose the belt 15 might be formed with holes efiecting communication between the opposite faces of the belt, so that the passage 34 would not have to extend across the outer face'of the belt in vorder to balance the fluid pressures thereon.

'The end wall of the intermediate casing member 21 is also formed with an internal passage 35, which extends from the passage 34 around to a passage 36 communicating with the space between the gear 10, the toothed inner face of belt 15 and the lower left corner of spacer plate 12 in Fig. 2, immediately adjacent the engagement of the belt with this gear. Passage 36 also communicates with the outer face of thebelt entirely thereacross to balance the pressures on the opposite faces of the belt at this location.

A threaded discharge passage 37 formed in the intermediate casing member 21 leads to high pressure passages 38 and 39 in chamber 25 which are interconnected .by an internal passage 40 formed in the end plate 20. The passage;38 communicates completely across the belt with the space between the gear 11, the belt 15 and the lower right corner of the spacer plate'in Fig. 2, as well as across the outer face of the belt thereat. Likewise, the high pressure passage 39 communicates completely across the belt with the space between the gear 10, the belt and the upper left corner of the spacer plate 12 in Fig. 2, as well as across the outer face of the belt at this location for pressure balancing purposes.

In the operation of this device, assuming that it is being operated as a pump, the gear is driven through a connection from a suitable prime mover (not shown), such as anelectric motor, to the drive shaft 41. The drive shaft is suitably connected to the gear journal 10a and is supported for rotation on the housing by a conventional ball bearing assembly 42. A seal 43 extends around the drive shaft to prevent leakage out of the housing along the drive shaft. 7 7

Assuming that the drive shaft rotates gear 10 counterclockwise in Fig.2, this gear will drive the belt 'counterclockwise, and the belt in turn will drive the other gear 11 in the same direction. Fluid drawn in through the low pressure passage 34 passes to the spaces between the teeth on gear 11 and to the spaces between the belt teeth thereat. As the gear 11 turns counterclockwise, the fluid in its intertooth spaces is carried around past the end face 14 of the spacer plate 12 to the high pressure discharge passage 38. The close running'fit of the gear 11 contact between the gears enables the pump to be employed for pumping fluids containing abrasives and the like, which is not feasible in conventional gear pumps cumference of each of thegears where the endless belt is,

in driving engagement with the gears.

Also, since approximately half the fluid pumped is carried in the intertooth spaces on the belt, the capacity of the pump is effectively double the capacity of a conven tional gear pump having gears of the same tooth depth and operating at the same speed.

From Fig 2, it will be observed that only a relatively small peripheral area of each of the gears 10 and 11 is exposed to the high pressure. fluid at the passages 38 and 39, so that the resultant unbalance thrusts on these gears is minimized proportionately. loads on these gears are less than in conventional gear pumps, where greater peripheral areas of the gears are In'the second embodiment of the present invention, illustrated in Fig. 3, there are provided four spaced spur gears -53 arranged in a square pattern. A fixed spacer block 54 separates the gears from one another and is formed with a first substantially semi-circular face 55 providing a close running clearance for the inwardly. disposed portion of the toothed periphery of gear 50, a second substantially semi-circular face 56 providing a close running clearance for the inner toothed peripheral por tion of gear 51, a third substantially semi-circular face 57 providing a close runningfit for the inwardly disposed portion of the toothed periphery of gear 52, and a fourth substantially semi-circular face 58 providing a close. running fit for the inner portion of the periphery of gear 53.

An endless flexible belt 59 of the type described in detail above extends around the gear and spacer assembly and has teeth at its inner face which mesh with the gear teeth on each ofthe gears. The spacer block 54 presents flat and faces 6063 located respectively be-- tween the gears and providing close running clearances for the toothed inner face of the endless belt thereat. The endless belt 59 hasa close running fit at its smooth outer face in the chamber 64 formed in the housing 65.

Within the housing there are provided a plurality 'of low pressure passages 66-69, which communicated respectively with the spaces between the toothed inner face of the endless belt, the spacer block'and the gears immediately adjacent where the belt meshes with the gears. In similar fashion, the high pressure passages 7073 coni- V V municate respectively with the spaces between the toothed at the arcuate end face 14 of the spacer plate 12 causes 7 the fluid to be trapped in these intertooth spaces on gear manner. The remainder of the fluid entering at the low pressure passage 34 is trapped in the intertooth spaces on belt 15 between the belt and the end face 17 of the spacer plate and is carried around to the high'pressure discharge passage 39 as the belt moves counterclockwise.

In like manner, a portion of the fluid entering at the low pressure passage 36 is carried by gear 10 around to the high pressure discharge passage 39, while the remainder of this fluid is carried by the belt 15 over to the other high pressure discharge passage 38. I

It will be noted that with this arrangement there is no engagement between the gears, the driving connection between the gears being effected by the belt, which results in much quieter operation and reduced wear. For this reason, if desired, the gears may be made of soft plastic inner face of the endless belt, the spacer block and .the gears, immediately adjacent the: opposite end of the en-v gagement of the belt with the respective gear. As in the firstdescribed embodiment of the invention, the high andlow pressure passages are arranged in alternate sequence along the belt. At each of the high and low pressure passages the outer face of the endless belt is exposed to around to the high pressure outlet 70 and by thebelt to the high pressure outlet 71, fluid drawn in at the suction inlet 68 is carried by gear 52 .around to the high'pres sure outlet 71 and by the belt over to the high pressure outlet 72, and fluid drawn in at the suction inlet 69 is carried by gear 53 around to the high pressure outlet 72 and by the belt over to the high pressure outlet 73. In

Therefore, the bearing this @Peration; the close: running clearances gprovided for 31the::gears;by: the :arcuate faces *58- on-.the;spacer cause the fluidtobetrapped in .theintertooth;spaceson the re- :spe'ctive-gearsy-while the close vrunningfits provided for the toothed inner face ofithe endless beltby'theflat end faces--63 cause-the fluid-to-jbe trapped ,in the intertooth. spaces on the belt and carried thereby between Ithegears from asuctioniinlet to theneXt-high-pressure outlet, as described. 7

In the. third: embodiment of the invention, shown in" a Fig. 3, there areprovidedthree-gears 8t,-81, $2 having their respectiveaxes of rotation disposed in one plane.

:A' fixed spacer block 83 separates f the: endgearv'sd from the larger, middlegear slrand is formed'with'v an ''arcuate end .face 84 which providesa close running clearance for therinwardly "disposed portion of the toothed peripheryof gear$0,las -well.as an arcuateopposite endface-35 providinga'closei running-clearance for. a portion of the periphery ofmiddlegearefil. .AlSlHlllZlI spacer block'86 separates'the middlergear :81 from the other: end gear 82,

being formed with. an: arcuateend face 87: providing a close runniugrfit'for the inwardly disposed peripheral portion of gear 82 and an opposite arcuateendface SS providing' a close running'fit for theradjacentportion of the periphery of middlergeafSl.

*An endless flexible belt 89' extends :around the assembly of: gears. and 'is formed with teeth 'atits' inner face meshinglWith theigear teeth. .Thetspacer block? 33: presents :Iflat end. faces-90 and 91 :which provide close: running "clearances for the opposite 'coursesoffthe belt"'89' between 1 the? gearslsiland 81. :Similarly, the OlhD'SPflCCI'TblOCk 1'86 presents flat end; faces 92 :and .93. providing .close run- I ning' clearances for .hte .oppositezc'oursestof belt 89. be-

tween the gears '81 anch 82. I Due toithe larger diameter or" the middle gear 81,:it. imparts at slight tension .to the beltj 89,.preventing the. belt ifrom slackening. an undesired amount. 'AtTiIS SmOOth outer:face-the*belt'=89 hasa'close running 'clearancein the chamber- 94 formed by the housing 95.

VVlthin the housing'there are provide'd a -plurality of low pressure passages 96- 99 communicating respectively with the spaces between the endless belt; the respective spacer blocks and the respective gearsimmediatelyadjacent the point of mesh'of eachgear -withthebelt. Also,

there are provided the-high-pressure: passages 1130-1103, which: communicate respectively-vvith' the spaces between the endless belt, therespective' spacer blocks-and-t-he respective gears at the opposite sides of the-spacer blocks from the low pressure passages, immediately-adjacent the engagementthereat of each gear withthebelt. As is clear from'Fjg. 4, these low and highpressurepassages Larearranged' in alternate sequence along"the'belt. The

. in at the low pressure inletpassage 96' is ic'arried'by the 'gearfio around to the highpressure outlet "passage 103 and by the belt over .to'ithe'high'pressureoutlet passage 1%, fluid drawnin at the'low pressure inlet passage 97 .is carried by thegear 8L around to the highpressure outlet .passageldl and by .the belt-overto the'highpressure outlet. passageltll, fiuidentering atrthe low pressure inlet v-passa'ge 98 is carried bygear-82 around to the high pressure outlet passagerlfiland-by theendless beltover-to the highepressure outletipassage :102, and fluid entering at the .loWpressureinlet-passage199 is carried by; gear- 81 around :tothehighr pressure: outletlpassage: 100 and by :the

endless b'elt' overto' the highipressuremutlebpassage" 103. At this time; the: close 'running clearancesprovided by the 88 of the spacer blocks 83 and 86 cause fluid to lie-trapped in thezintertooth spaces on the middle gear- 81 and carried from the lowpressure passagesto the -high pressure passages, as described, and the close running clearance provided by .the arcuate end face 87 of spacer-block 86 causes the entrapment of fluidin the intertooth spaces on gear 82. In like manner, fluidis trapped inthe intertooth spaces on the endless belt-89 due to the close running clearances provided-for the toothed inner face of the belt by the flat end'faces of .the spacer blocks, -for the .transfer of fluid between the inlet and outlet-passages inthe manner outlined above.

In the final embodiment of the invention, shown in-Eig. 5, the endless belt is formed withteeth atbothitsinner and outer .faces and meshes at. both of these faces with the gears for pumping fluid. Thus, as "shown in Eig. 5, the two spaceddnnergears and lllmeshwith the toothed inner face of the flexiblebelt 112. The spacer block 113 separates these gears and has arcuate end faces 114, 115 providing close running clearances for-these gears and flat end faces 116, 117. providing close running clearances tor the toothed-inner face-of the endless belt -112, as inthe first described embodiment of the present invention. Aiternately arranged lowpressure and high pressure passages 118, .119, 129 and- 121 communicate with-the respective spaces between each-.geantheendless belt-and the spacer block for passing fluid-to and from: the toothed peripheries of the gears 110 and 111 andthe toothed inner face of the endless belt 112. i p .The housing122 Which-encloses'themsse bly of the inner gearslll), 1'11 andtheendlessbelt 1-1-2-also encloses an outer gear I123 positioned to mesh with the toothed outer faceof the endless belt, sothat this-outen gearis 'driven by the belt. With theinner.-gears-1=10, 111. and the endless belt l12all turning'clockwise-in Fig-:5, the endless belt drives the outer gear 123 in the opposite-direction. i

The housing 122 is formed with a bore-124 receiving .theouter gear 123 and'providing aclose running fit there for between the low pressure passage- 125-end the high pressure passage 126. This bore l24 intersects-the oblong chamber 127 in 'the-housing122 whichprovidesa close running fit for the endless belt.

I in the operation of this 1 device, assuming pump operation, fluid drawn in atthe low pressure inlet 118 is-carried by gear 110 around to thehigh pressure-.outlet-IZLand by the toothed inner face of endless --belt 112"over-to-the high pressure outlet 119, fluid ienteriug at the'low-pressure inlet 124i is-carried by gear 111 around to the. high :pressure outlet 119 and by the toothed inner faceof belt 1 .112 events the high pressure outlet 121,".While fluid entering the low pressure inlet 125 is carried byngear 123 around to the high pressure outlet-126. Of eourse,-a-por- -=ti0n of the fluid entering at the low v pressure inletpassage 125 is carried in the inter-tooth spacesonthe outenface of the endless belt 112 -around to thehigh pressure outlet :passage 126.

lt-will be obvious that'the principle-of operation ofthe Fig. Sdevice may be extended to include-two or more outer gears, one such additional-;outer.=.-gear -being, -sho\vn in dotted lines in Fig. -5. Since the flexible endlessjbelt forms 'the'drive for the outer gears, any number. of. such outer-gears which-maybe conveniently grouped-about the outer face of thebelt may be provided, asdesired. Also, -With such outer gear assemblyany'desired arrangement of the inner gears encircled by the endless belt may-be provided, such as the four gear arrangementof Fig; 3 or the three gear arrangement of Fig. '4.

-While in' the foregoing description: and in the accompanying drawings there have been disclosed severalipreferred embodiments of the, present invention, it. is to=be understood that 'various' modifications,- omissions::-and refinetnents which depart from disclosed forms of the invention may be adopted without departing from the spirit and scope of the present invention.

' I claim: a

vl; A pump or fluid motorcomprising spaced first and i second rotary toothed gears, an endless'fiexible belt extending around said gears and formed at its inner face with spaced teeth received in the spacesbetween teeth on said gears, a housing enclosing said gears and said belt and having portions disposed in close running 'fit with the ends of'said gears and belt, a'spacer disposed'between the spaced gearsand formed with spaced arcuate opposite end faces extending respectively closely adjacent the toothed peripheral portions of the gears which are closest to one another and providing close running fits thereat for said gears; said spacer being formed with spaced fiat opposite end faces extending closely adjacent opposed por-.

tions of-the toothed inner face of the belt between said gears, a first high pressure passage in thehousing communicating with the space between said first gear, said ner face of the belt, a first low pressure passage in said housing communicating with the space between the second gear, said spacer and said one opposed portion of the toothed'inner-face of the belt, a second high pressurepasf sage in the housing communicating with the space be-' tween the second gear, said'spacer and the other of said opposed portions of the toothed inner face of the belt, and

V a second low pressure passage in the housing communicating with the space between the first gear, said spacer and said other opposed portion of the toothed inner face of the belt. Y v

2. A pump or fluid motor comprising spaced first and second rotary gears, a flexible endless belt extending around'said gears and formed atits inner face with spaced teeth meshing with the 'gear teeth at the outer peripheral portions of the respective gears, a housing enclosing said gears and said belt and having portions disposed in close running fit with the ends of said gears and belt, a spacer. plate disposed between the gears and surrounded by the belt, :said spacer plate having arcuate end faces shaped substantially complementary to the' inwardly disposed peripheral portions of the gears and extending closely adjacent thereto and providing close running fits thereat for the gears, said spacer plate being formed with flat end faces extending closely adjacent the opposed courses of the toothed inner face of the belt between the gears, a first high pressure passage in the housing at one end of the inwardly disposed peripheral portion of the first gear and communicating thereat with the space between said first gear, a first one of said opposed courses of the toothed inner faceof the belt and said spacer plate, a first low pressure passage in the housing at said end of the'inwardly disposed peripheralportion of the second gear and communicating thereat with the space between said I second gear, said first one of the opposed courses of the toothed inner face of the belt and said spacer plate, a second high pressure passage in the'housin'g at the opposite end of the inwardly disposed peripheral portion of said second gear and communicating thereat with the .space closing said gears and said'belt and posed in close running fit with the ends of said gears and belt, a spacer disposed between the spaced gears, said spacer having'arcuate end faces extending respectively closely adjacent the inwardly disposed peripheral portions of the gears and providing close running clearances therefor, said spacer being formed with 'fiat'end faces-extend- 'ing closely adjacenfthe toothed inner face of the belt spacer and one of said opposed portions of the toothed ining gear, the toothed inner face of the belt and the spacer,

said high and low pressure passages being arranged in alternate sequence along the belt for the supply of fluid at alternate ones of said passages to the intertooth spaces on the gears and the belt and the discharge of. fluid atthe others of said passages from said intcrtooth spaces on the gears and the belt.

4. A pump or fluid motor comprising an even numbered plurality of gears, greater than two, an endless flexible belt 7 extending around said gears and formed of apliable material to conform to the peripheriesof the gears and extend in a straight line from the periphery of one gear to the periphery of 'an adjacent gear, said beltfbeing formed'at its inner face with spaced teeth meshing with the teeth on each gear located at the outwardly disposed peripheralportion thereof, a housing enclosing Fs'aid gears andsaid between said second gear, the other of said opposed space between said first gear, said other opposed course'of courses of'the toothedinner face of the belt and said spacer plate, and a'second low pressure passage, in the housing at 3 said opposite endof the inwardly disposed peripheral portion 'of saidfirst gear and communicating thereat with the tions thereof and meshing with the teeth on the fmiddle gear at opposite peripheral'portions thereof, a housing enclosing said gears and thebelt and having portions disv posed in close running fitwith the ends of said gears and the toothed innerface of the belt and said spacer plate.

3. A pump or fluid motor comprising four spaced rotary gears, an endless flexihie'beit extending around said gears and formed of a pliable material to conform to the peripheries of thegearsand extend in a straight line from the periphery of'one gear to the periphery of an adjacent gear, said belt being formed at its inner face with spaced teeth meshingwith the teeth on each gear located at the outwardly disposed peripheralportion thereof, a housing en- .belt and having portions; disposed in close runningfit with the ends of said gears and belt," a spacer disposedbetween the, spaced. gears, said spacer having arcuate 'end faces extending respectively closely adjacent the inwardly disposed peripheral portions of the gears and providing closerunning clearances therefor, said spacer being forcedwith flat end faces extending closely adjacent the toothed inner faceof the belt between each pair of adjacent gears, high pressure passages ;in the housing at one end of each of said arcuate end faces on the spacer and communicating thereat With the respective space between the corresponding gear, the toothed inner face of the belt and thespacer,

and low pressure passages in the housing at the respective opposite ends of said arcuate end faces on the spacer and communicating thereat with the respective space between the corresponding gear, the toothed inner face of the belt and the spacer, said high and low pressure passages being arranged in alternate sequence along the belt for the supply of fluid at alternate ones of said passages to the intertooth spaces on the gears and the belt and the discharge of fluid at the others of said passages from said intertooth,

spaces on the gears and the belt. H

5. A rotary pump or fluid motor comprising apair of spaced end gears and a middle gear located therebetween in spaced relation from both end gears an endless flexible belt extending around said gears and adapted to'conform to the peripheries of the gears and extend in a straight line from the periphery of one gear to the periphery of an adjacent gear, said endless belt being'formed with spaced teeth on its inner facemeshing with the teeth on ,thesend gears located atthe outwardly disposed peripheral porbelt, a first spacer disposed between the rniddle'gear and a first one of said end gears, said first spacer having opposite arcuate end faces extending respectively closely adjacent the inwardly disposed peripheral portion of said first end gear and the adjacent peripheral portion of the middle gear and providing close running clearances thereat for said gears, said first spacer having opposite flat end I faces extending closely adjacent the toothed inner face of having portions dis ting -245,355

1' 9 the belt betweensaid first eiid gear and the middle gear and providing close running clearances forthe belt there- ..at, a second spacer disposed betweenthe middle gear and the other end gear, said second spacer having'opposite arcuate endfaces extending respectively closely; adjacent -the inwardly disposed peripheral portion of .said. other and gear and the adjacent peripheral portion of the middle gear and providing close running clearances :thereat for said gears, said second spacer having opposite flat end faces extending closely adjacent the toothed inner'face of the belt between said other end gear and the middle gear and providing close runningclearances for the belt Tthereat,-high pressure passages 'in thehousing. at one end 1 of each of. said arcuate end faces onethe spacers and com- .municating thereat with the respective space between the corresponding gear, the toothed inner face of the belt and the corresponding spacer, and low pressure passages in the housing at the respective opposite ends of the arcuate end faces on the spacers and communicating thereat with the respective space between the corresponding gear, the toothed inner face of the belt and the corresponding spacer, said high and low pressure passages being arranged in alternate sequence along the belt for the supply of fluid at alternate ones of said passages to the intertooth spaces on the gears and the belt and the discharge of fluid at the others of said passages from said intertooth spaces on the gears and the belt.

6. The device of claim 5, wherein said middle gear is larger in diameter than either of said end gears.

7. The device of claim 5, wherein said gears have their respective axis of rotation lying substantially in the same plane.

8. A fluid pump or motor comprising a plurality of spaced rotary gears separated from one another and mounted for rotation on parallel axes, said gears having gear teeth formed on the periphery thereof, an endless flexible belt passing around said gears adapted to conform to the gear peripheries and extend in a straight line from the periphery of one gear to the periphery of an adjacent gear, said belt having gear teeth extending across the inner face thereof and shaped to mesh with the teeth on the gears to be driven thereby in a closed path disposed normal to the axes of said gears, and a housing enclosing said gears and belt and having spaced high and low pressure passages therein between the gears and belt at the points of meshing engagement and disengagement of the belt with the gears, said housing having portions extending closely adjacent the toothed peripheries of the gears and the toothed inner face of the belt and also portions disposed in close running fit with the ends of the gears and belt intermediate each high and low pressure passage to form a running seal between each high and loW pressure passage.

9. The combination of claim 8 wherein said high pressure passages each communicate with the outer face of the belt as well as at the toothed inner face thereof to balance the fluid pressure on the opposite faces of the belt at said high pressure passages.

10. The combination of claim 8 including means for applying fluid pressure at the outer face of the belt equal to the fluid pressure on the inner face thereof at each of the high pressure passages to balance the fluid pressure on opposite faces of the belt at said high pressure passages.

11. A fluid pump or motor comprising a plurality of spaced rotary gears separated from one another and mounted for rotation .on parallel axes, said gears having gear teeth formed on the periphery thereof, an endless flexible belt passing around said gears adapted to conform to the gear peripheries and extend in a straight line from the periphery of one gear to the periphery of an adjacent gear, said belt having gear teeth extending across the inner face thereof and shaped to mesh with the teeth on the gears, to be driven thereby in a closed path disposed normal to the axes of said gears, a housing enclosing .-said.;gears;and belt:':and havingx-ppacedhigh and low'pressure passages thereinzbetween the gears-and beltat the. points of meshingengagement.andsdisengagement of the belt Withthe. gears, and spacer means separating the gears and extending.closelyradjacent the toothed inner face of the belt "between :the gears and having curved faces extending closely adjacent the mutually adjacent'peripheral portions of.the=gears, said housing having portions extending closely adjacent the end faces of the gears and belt between eachof said high andlow pressure passages 'toithereby form a running seal between each high and lowpressure passages.

12. A fluid'pump or motor; comprising a pluralityof spaced rotary gears mounted for rotation on parallel axes and each formed with a cylindrical periphery having gear teeth extending thereacross, an endless flexible belt passing around said gears and formed of a pliable material to conform to the peripheries of said gears and extend in a straight line from the periphery of one gear to the periphery of an adjacent gear, said belt having a plurality of teeth extending across the inner face thereof and shaped to mesh with the teeth on the gears to be driven thereby in a closed loop disposed normal to the axes of said gears, a housing enclosing said gears and belt and having spaced high and low pressure passages therein between the gears and the belt at the points of meshing engagement and disengagement of the belt with the gears, said housing having portions extending closely adjacent the toothed peripheries of the gears and the toothed inner face of the belt and also portions disposed in close running fit with the ends of the gears and belt and in close running fit with the outer side of the belt intermediate each high and low pressure passage to form a running seal between each pair of high and low pressure passages.

13. A fluid pump or motor comprising a plurality of spaced rotary gears formed with gear teeth on the peripheries thereof and mounted for rotation about parallel axes, an endless flexible belt passing around said gears and formed of a pliable material to conform to the gear peripheries and extend in a straight line from the periphery of one gear to the periphery of an adjacent gear, said belt having a smooth outer face and formed at its inner face with a plurality of teeth spaced apart along the length of the belt and shaped to mesh with the teeth on the gears, spacer means separating the gears and formed with arcuate faces extending closely adjacent the mutually adjacent portions of the gears and flat end faces extending closely adjacent the straight inner faces of the belt between the gears, a housing enclosing said gear, belt and spaced means and closely overlying the ends of said gears and belt and closely overlying the smooth outer periphery of said belt, said housing having high and low pressure passages therein between the periphery of the gears, the toothed inner face of the belt and said spacer means at the points of meshing engagement and disengagement of the belt with the gears, said high and low pressure passages being disposed alternate sequence along the belt for the admission of fluid at alternate ones of said passages to the intertcoth spaces on the gears and the belt and the discharge of fluid at the others of said passages from the intertooth spaces of the gears and belt.

14. A fluid pump or motor comprising a gear as sembly including a plurality of spaced rotary gears formed with gear teeth on the peripheries thereof and mounted for rotation about parallel axes, an endless belt passing around said gear assembly and formed of a pliable material to conform to the peripheries of said gears and extend in a straight line therebetween, said belt having teeth formed on the inner face thereof shaped to mesh with the teeth on said gears, said belt also having teeth formed on the outer face thereof, a gear disposed outside of said belt in meshing engagement with the teeth on the outer face thereof, a housing enclosing said gears and belt and having high and low pressure passages therein at the points of meshing engagement and disengageof the gear external of said belt between the points of" meshing engagement and disengagement of each gear with V the belt; said housing'also having portions disposed in close running fit with the ends of the; gears and belt be-V tween the points of meshing engagement and disengagement of the gears with said belt, and portions on said housing disposed in close running fit'with the outer face of said belt between the points of meshing engagement and disengagement of the-gear disposed externally of said belt.

7UNITED STATES PATENTS- Murray; Mari 124', 1908 Stevens Dec. 28; 1909' i Bartlett 'June 10, 1919 Kerr Sept. 5, 1922 Seagren Feb; 21, 1939 [Melville Nov. 10',1942 Neal Feb. 29, 1944 FOREIGN PATENTS Great Britain Apr. 1, 1937 France Mar. 27, 1923 

